libstdc++
hashtable_policy.h
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00001 // Internal policy header for unordered_set and unordered_map -*- C++ -*-
00002 
00003 // Copyright (C) 2010-2017 Free Software Foundation, Inc.
00004 //
00005 // This file is part of the GNU ISO C++ Library.  This library is free
00006 // software; you can redistribute it and/or modify it under the
00007 // terms of the GNU General Public License as published by the
00008 // Free Software Foundation; either version 3, or (at your option)
00009 // any later version.
00010 
00011 // This library is distributed in the hope that it will be useful,
00012 // but WITHOUT ANY WARRANTY; without even the implied warranty of
00013 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00014 // GNU General Public License for more details.
00015 
00016 // Under Section 7 of GPL version 3, you are granted additional
00017 // permissions described in the GCC Runtime Library Exception, version
00018 // 3.1, as published by the Free Software Foundation.
00019 
00020 // You should have received a copy of the GNU General Public License and
00021 // a copy of the GCC Runtime Library Exception along with this program;
00022 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
00023 // <http://www.gnu.org/licenses/>.
00024 
00025 /** @file bits/hashtable_policy.h
00026  *  This is an internal header file, included by other library headers.
00027  *  Do not attempt to use it directly.
00028  *  @headername{unordered_map,unordered_set}
00029  */
00030 
00031 #ifndef _HASHTABLE_POLICY_H
00032 #define _HASHTABLE_POLICY_H 1
00033 
00034 #include <bits/stl_algobase.h> // for std::min.
00035 
00036 namespace std _GLIBCXX_VISIBILITY(default)
00037 {
00038 _GLIBCXX_BEGIN_NAMESPACE_VERSION
00039 
00040   template<typename _Key, typename _Value, typename _Alloc,
00041            typename _ExtractKey, typename _Equal,
00042            typename _H1, typename _H2, typename _Hash,
00043            typename _RehashPolicy, typename _Traits>
00044     class _Hashtable;
00045 
00046 _GLIBCXX_END_NAMESPACE_VERSION
00047 
00048 namespace __detail
00049 {
00050 _GLIBCXX_BEGIN_NAMESPACE_VERSION
00051 
00052   /**
00053    *  @defgroup hashtable-detail Base and Implementation Classes
00054    *  @ingroup unordered_associative_containers
00055    *  @{
00056    */
00057   template<typename _Key, typename _Value,
00058            typename _ExtractKey, typename _Equal,
00059            typename _H1, typename _H2, typename _Hash, typename _Traits>
00060     struct _Hashtable_base;
00061 
00062   // Helper function: return distance(first, last) for forward
00063   // iterators, or 0 for input iterators.
00064   template<class _Iterator>
00065     inline typename std::iterator_traits<_Iterator>::difference_type
00066     __distance_fw(_Iterator __first, _Iterator __last,
00067                   std::input_iterator_tag)
00068     { return 0; }
00069 
00070   template<class _Iterator>
00071     inline typename std::iterator_traits<_Iterator>::difference_type
00072     __distance_fw(_Iterator __first, _Iterator __last,
00073                   std::forward_iterator_tag)
00074     { return std::distance(__first, __last); }
00075 
00076   template<class _Iterator>
00077     inline typename std::iterator_traits<_Iterator>::difference_type
00078     __distance_fw(_Iterator __first, _Iterator __last)
00079     {
00080       typedef typename std::iterator_traits<_Iterator>::iterator_category _Tag;
00081       return __distance_fw(__first, __last, _Tag());
00082     }
00083 
00084   // Helper type used to detect whether the hash functor is noexcept.
00085   template <typename _Key, typename _Hash>
00086     struct __is_noexcept_hash : std::__bool_constant<
00087         noexcept(declval<const _Hash&>()(declval<const _Key&>()))>
00088     { };
00089 
00090   struct _Identity
00091   {
00092     template<typename _Tp>
00093       _Tp&&
00094       operator()(_Tp&& __x) const
00095       { return std::forward<_Tp>(__x); }
00096   };
00097 
00098   struct _Select1st
00099   {
00100     template<typename _Tp>
00101       auto
00102       operator()(_Tp&& __x) const
00103       -> decltype(std::get<0>(std::forward<_Tp>(__x)))
00104       { return std::get<0>(std::forward<_Tp>(__x)); }
00105   };
00106 
00107   template<typename _NodeAlloc>
00108     struct _Hashtable_alloc;
00109 
00110   // Functor recycling a pool of nodes and using allocation once the pool is
00111   // empty.
00112   template<typename _NodeAlloc>
00113     struct _ReuseOrAllocNode
00114     {
00115     private:
00116       using __node_alloc_type = _NodeAlloc;
00117       using __hashtable_alloc = _Hashtable_alloc<__node_alloc_type>;
00118       using __value_alloc_type = typename __hashtable_alloc::__value_alloc_type;
00119       using __value_alloc_traits =
00120         typename __hashtable_alloc::__value_alloc_traits;
00121       using __node_alloc_traits =
00122         typename __hashtable_alloc::__node_alloc_traits;
00123       using __node_type = typename __hashtable_alloc::__node_type;
00124 
00125     public:
00126       _ReuseOrAllocNode(__node_type* __nodes, __hashtable_alloc& __h)
00127         : _M_nodes(__nodes), _M_h(__h) { }
00128       _ReuseOrAllocNode(const _ReuseOrAllocNode&) = delete;
00129 
00130       ~_ReuseOrAllocNode()
00131       { _M_h._M_deallocate_nodes(_M_nodes); }
00132 
00133       template<typename _Arg>
00134         __node_type*
00135         operator()(_Arg&& __arg) const
00136         {
00137           if (_M_nodes)
00138             {
00139               __node_type* __node = _M_nodes;
00140               _M_nodes = _M_nodes->_M_next();
00141               __node->_M_nxt = nullptr;
00142               __value_alloc_type __a(_M_h._M_node_allocator());
00143               __value_alloc_traits::destroy(__a, __node->_M_valptr());
00144               __try
00145                 {
00146                   __value_alloc_traits::construct(__a, __node->_M_valptr(),
00147                                                   std::forward<_Arg>(__arg));
00148                 }
00149               __catch(...)
00150                 {
00151                   __node->~__node_type();
00152                   __node_alloc_traits::deallocate(_M_h._M_node_allocator(),
00153                                                   __node, 1);
00154                   __throw_exception_again;
00155                 }
00156               return __node;
00157             }
00158           return _M_h._M_allocate_node(std::forward<_Arg>(__arg));
00159         }
00160 
00161     private:
00162       mutable __node_type* _M_nodes;
00163       __hashtable_alloc& _M_h;
00164     };
00165 
00166   // Functor similar to the previous one but without any pool of nodes to
00167   // recycle.
00168   template<typename _NodeAlloc>
00169     struct _AllocNode
00170     {
00171     private:
00172       using __hashtable_alloc = _Hashtable_alloc<_NodeAlloc>;
00173       using __node_type = typename __hashtable_alloc::__node_type;
00174 
00175     public:
00176       _AllocNode(__hashtable_alloc& __h)
00177         : _M_h(__h) { }
00178 
00179       template<typename _Arg>
00180         __node_type*
00181         operator()(_Arg&& __arg) const
00182         { return _M_h._M_allocate_node(std::forward<_Arg>(__arg)); }
00183 
00184     private:
00185       __hashtable_alloc& _M_h;
00186     };
00187 
00188   // Auxiliary types used for all instantiations of _Hashtable nodes
00189   // and iterators.
00190 
00191   /**
00192    *  struct _Hashtable_traits
00193    *
00194    *  Important traits for hash tables.
00195    *
00196    *  @tparam _Cache_hash_code  Boolean value. True if the value of
00197    *  the hash function is stored along with the value. This is a
00198    *  time-space tradeoff.  Storing it may improve lookup speed by
00199    *  reducing the number of times we need to call the _Equal
00200    *  function.
00201    *
00202    *  @tparam _Constant_iterators  Boolean value. True if iterator and
00203    *  const_iterator are both constant iterator types. This is true
00204    *  for unordered_set and unordered_multiset, false for
00205    *  unordered_map and unordered_multimap.
00206    *
00207    *  @tparam _Unique_keys  Boolean value. True if the return value
00208    *  of _Hashtable::count(k) is always at most one, false if it may
00209    *  be an arbitrary number. This is true for unordered_set and
00210    *  unordered_map, false for unordered_multiset and
00211    *  unordered_multimap.
00212    */
00213   template<bool _Cache_hash_code, bool _Constant_iterators, bool _Unique_keys>
00214     struct _Hashtable_traits
00215     {
00216       using __hash_cached = __bool_constant<_Cache_hash_code>;
00217       using __constant_iterators = __bool_constant<_Constant_iterators>;
00218       using __unique_keys = __bool_constant<_Unique_keys>;
00219     };
00220 
00221   /**
00222    *  struct _Hash_node_base
00223    *
00224    *  Nodes, used to wrap elements stored in the hash table.  A policy
00225    *  template parameter of class template _Hashtable controls whether
00226    *  nodes also store a hash code. In some cases (e.g. strings) this
00227    *  may be a performance win.
00228    */
00229   struct _Hash_node_base
00230   {
00231     _Hash_node_base* _M_nxt;
00232 
00233     _Hash_node_base() noexcept : _M_nxt() { }
00234 
00235     _Hash_node_base(_Hash_node_base* __next) noexcept : _M_nxt(__next) { }
00236   };
00237 
00238   /**
00239    *  struct _Hash_node_value_base
00240    *
00241    *  Node type with the value to store.
00242    */
00243   template<typename _Value>
00244     struct _Hash_node_value_base : _Hash_node_base
00245     {
00246       typedef _Value value_type;
00247 
00248       __gnu_cxx::__aligned_buffer<_Value> _M_storage;
00249 
00250       _Value*
00251       _M_valptr() noexcept
00252       { return _M_storage._M_ptr(); }
00253 
00254       const _Value*
00255       _M_valptr() const noexcept
00256       { return _M_storage._M_ptr(); }
00257 
00258       _Value&
00259       _M_v() noexcept
00260       { return *_M_valptr(); }
00261 
00262       const _Value&
00263       _M_v() const noexcept
00264       { return *_M_valptr(); }
00265     };
00266 
00267   /**
00268    *  Primary template struct _Hash_node.
00269    */
00270   template<typename _Value, bool _Cache_hash_code>
00271     struct _Hash_node;
00272 
00273   /**
00274    *  Specialization for nodes with caches, struct _Hash_node.
00275    *
00276    *  Base class is __detail::_Hash_node_value_base.
00277    */
00278   template<typename _Value>
00279     struct _Hash_node<_Value, true> : _Hash_node_value_base<_Value>
00280     {
00281       std::size_t  _M_hash_code;
00282 
00283       _Hash_node*
00284       _M_next() const noexcept
00285       { return static_cast<_Hash_node*>(this->_M_nxt); }
00286     };
00287 
00288   /**
00289    *  Specialization for nodes without caches, struct _Hash_node.
00290    *
00291    *  Base class is __detail::_Hash_node_value_base.
00292    */
00293   template<typename _Value>
00294     struct _Hash_node<_Value, false> : _Hash_node_value_base<_Value>
00295     {
00296       _Hash_node*
00297       _M_next() const noexcept
00298       { return static_cast<_Hash_node*>(this->_M_nxt); }
00299     };
00300 
00301   /// Base class for node iterators.
00302   template<typename _Value, bool _Cache_hash_code>
00303     struct _Node_iterator_base
00304     {
00305       using __node_type = _Hash_node<_Value, _Cache_hash_code>;
00306 
00307       __node_type*  _M_cur;
00308 
00309       _Node_iterator_base(__node_type* __p) noexcept
00310       : _M_cur(__p) { }
00311 
00312       void
00313       _M_incr() noexcept
00314       { _M_cur = _M_cur->_M_next(); }
00315     };
00316 
00317   template<typename _Value, bool _Cache_hash_code>
00318     inline bool
00319     operator==(const _Node_iterator_base<_Value, _Cache_hash_code>& __x,
00320                const _Node_iterator_base<_Value, _Cache_hash_code >& __y)
00321     noexcept
00322     { return __x._M_cur == __y._M_cur; }
00323 
00324   template<typename _Value, bool _Cache_hash_code>
00325     inline bool
00326     operator!=(const _Node_iterator_base<_Value, _Cache_hash_code>& __x,
00327                const _Node_iterator_base<_Value, _Cache_hash_code>& __y)
00328     noexcept
00329     { return __x._M_cur != __y._M_cur; }
00330 
00331   /// Node iterators, used to iterate through all the hashtable.
00332   template<typename _Value, bool __constant_iterators, bool __cache>
00333     struct _Node_iterator
00334     : public _Node_iterator_base<_Value, __cache>
00335     {
00336     private:
00337       using __base_type = _Node_iterator_base<_Value, __cache>;
00338       using __node_type = typename __base_type::__node_type;
00339 
00340     public:
00341       typedef _Value                                    value_type;
00342       typedef std::ptrdiff_t                            difference_type;
00343       typedef std::forward_iterator_tag                 iterator_category;
00344 
00345       using pointer = typename std::conditional<__constant_iterators,
00346                                                 const _Value*, _Value*>::type;
00347 
00348       using reference = typename std::conditional<__constant_iterators,
00349                                                   const _Value&, _Value&>::type;
00350 
00351       _Node_iterator() noexcept
00352       : __base_type(0) { }
00353 
00354       explicit
00355       _Node_iterator(__node_type* __p) noexcept
00356       : __base_type(__p) { }
00357 
00358       reference
00359       operator*() const noexcept
00360       { return this->_M_cur->_M_v(); }
00361 
00362       pointer
00363       operator->() const noexcept
00364       { return this->_M_cur->_M_valptr(); }
00365 
00366       _Node_iterator&
00367       operator++() noexcept
00368       {
00369         this->_M_incr();
00370         return *this;
00371       }
00372 
00373       _Node_iterator
00374       operator++(int) noexcept
00375       {
00376         _Node_iterator __tmp(*this);
00377         this->_M_incr();
00378         return __tmp;
00379       }
00380     };
00381 
00382   /// Node const_iterators, used to iterate through all the hashtable.
00383   template<typename _Value, bool __constant_iterators, bool __cache>
00384     struct _Node_const_iterator
00385     : public _Node_iterator_base<_Value, __cache>
00386     {
00387     private:
00388       using __base_type = _Node_iterator_base<_Value, __cache>;
00389       using __node_type = typename __base_type::__node_type;
00390 
00391     public:
00392       typedef _Value                                    value_type;
00393       typedef std::ptrdiff_t                            difference_type;
00394       typedef std::forward_iterator_tag                 iterator_category;
00395 
00396       typedef const _Value*                             pointer;
00397       typedef const _Value&                             reference;
00398 
00399       _Node_const_iterator() noexcept
00400       : __base_type(0) { }
00401 
00402       explicit
00403       _Node_const_iterator(__node_type* __p) noexcept
00404       : __base_type(__p) { }
00405 
00406       _Node_const_iterator(const _Node_iterator<_Value, __constant_iterators,
00407                            __cache>& __x) noexcept
00408       : __base_type(__x._M_cur) { }
00409 
00410       reference
00411       operator*() const noexcept
00412       { return this->_M_cur->_M_v(); }
00413 
00414       pointer
00415       operator->() const noexcept
00416       { return this->_M_cur->_M_valptr(); }
00417 
00418       _Node_const_iterator&
00419       operator++() noexcept
00420       {
00421         this->_M_incr();
00422         return *this;
00423       }
00424 
00425       _Node_const_iterator
00426       operator++(int) noexcept
00427       {
00428         _Node_const_iterator __tmp(*this);
00429         this->_M_incr();
00430         return __tmp;
00431       }
00432     };
00433 
00434   // Many of class template _Hashtable's template parameters are policy
00435   // classes.  These are defaults for the policies.
00436 
00437   /// Default range hashing function: use division to fold a large number
00438   /// into the range [0, N).
00439   struct _Mod_range_hashing
00440   {
00441     typedef std::size_t first_argument_type;
00442     typedef std::size_t second_argument_type;
00443     typedef std::size_t result_type;
00444 
00445     result_type
00446     operator()(first_argument_type __num,
00447                second_argument_type __den) const noexcept
00448     { return __num % __den; }
00449   };
00450 
00451   /// Default ranged hash function H.  In principle it should be a
00452   /// function object composed from objects of type H1 and H2 such that
00453   /// h(k, N) = h2(h1(k), N), but that would mean making extra copies of
00454   /// h1 and h2.  So instead we'll just use a tag to tell class template
00455   /// hashtable to do that composition.
00456   struct _Default_ranged_hash { };
00457 
00458   /// Default value for rehash policy.  Bucket size is (usually) the
00459   /// smallest prime that keeps the load factor small enough.
00460   struct _Prime_rehash_policy
00461   {
00462     using __has_load_factor = std::true_type;
00463 
00464     _Prime_rehash_policy(float __z = 1.0) noexcept
00465     : _M_max_load_factor(__z), _M_next_resize(0) { }
00466 
00467     float
00468     max_load_factor() const noexcept
00469     { return _M_max_load_factor; }
00470 
00471     // Return a bucket size no smaller than n.
00472     std::size_t
00473     _M_next_bkt(std::size_t __n) const;
00474 
00475     // Return a bucket count appropriate for n elements
00476     std::size_t
00477     _M_bkt_for_elements(std::size_t __n) const
00478     { return __builtin_ceil(__n / (long double)_M_max_load_factor); }
00479 
00480     // __n_bkt is current bucket count, __n_elt is current element count,
00481     // and __n_ins is number of elements to be inserted.  Do we need to
00482     // increase bucket count?  If so, return make_pair(true, n), where n
00483     // is the new bucket count.  If not, return make_pair(false, 0).
00484     std::pair<bool, std::size_t>
00485     _M_need_rehash(std::size_t __n_bkt, std::size_t __n_elt,
00486                    std::size_t __n_ins) const;
00487 
00488     typedef std::size_t _State;
00489 
00490     _State
00491     _M_state() const
00492     { return _M_next_resize; }
00493 
00494     void
00495     _M_reset() noexcept
00496     { _M_next_resize = 0; }
00497 
00498     void
00499     _M_reset(_State __state)
00500     { _M_next_resize = __state; }
00501 
00502     static const std::size_t _S_growth_factor = 2;
00503 
00504     float               _M_max_load_factor;
00505     mutable std::size_t _M_next_resize;
00506   };
00507 
00508   /// Range hashing function assuming that second arg is a power of 2.
00509   struct _Mask_range_hashing
00510   {
00511     typedef std::size_t first_argument_type;
00512     typedef std::size_t second_argument_type;
00513     typedef std::size_t result_type;
00514 
00515     result_type
00516     operator()(first_argument_type __num,
00517                second_argument_type __den) const noexcept
00518     { return __num & (__den - 1); }
00519   };
00520 
00521   /// Compute closest power of 2.
00522   _GLIBCXX14_CONSTEXPR
00523   inline std::size_t
00524   __clp2(std::size_t __n) noexcept
00525   {
00526 #if __SIZEOF_SIZE_T__ >= 8
00527     std::uint_fast64_t __x = __n;
00528 #else
00529     std::uint_fast32_t __x = __n;
00530 #endif
00531     // Algorithm from Hacker's Delight, Figure 3-3.
00532     __x = __x - 1;
00533     __x = __x | (__x >> 1);
00534     __x = __x | (__x >> 2);
00535     __x = __x | (__x >> 4);
00536     __x = __x | (__x >> 8);
00537     __x = __x | (__x >>16);
00538 #if __SIZEOF_SIZE_T__ >= 8
00539     __x = __x | (__x >>32);
00540 #endif
00541     return __x + 1;
00542   }
00543 
00544   /// Rehash policy providing power of 2 bucket numbers. Avoids modulo
00545   /// operations.
00546   struct _Power2_rehash_policy
00547   {
00548     using __has_load_factor = std::true_type;
00549 
00550     _Power2_rehash_policy(float __z = 1.0) noexcept
00551     : _M_max_load_factor(__z), _M_next_resize(0) { }
00552 
00553     float
00554     max_load_factor() const noexcept
00555     { return _M_max_load_factor; }
00556 
00557     // Return a bucket size no smaller than n (as long as n is not above the
00558     // highest power of 2).
00559     std::size_t
00560     _M_next_bkt(std::size_t __n) noexcept
00561     {
00562       const auto __max_width = std::min<size_t>(sizeof(size_t), 8);
00563       const auto __max_bkt = size_t(1) << (__max_width * __CHAR_BIT__ - 1);
00564       std::size_t __res = __clp2(__n);
00565 
00566       if (__res == __n)
00567         __res <<= 1;
00568 
00569       if (__res == 0)
00570         __res = __max_bkt;
00571 
00572       if (__res == __max_bkt)
00573         // Set next resize to the max value so that we never try to rehash again
00574         // as we already reach the biggest possible bucket number.
00575         // Note that it might result in max_load_factor not being respected.
00576         _M_next_resize = std::size_t(-1);
00577       else
00578         _M_next_resize
00579           = __builtin_ceil(__res * (long double)_M_max_load_factor);
00580 
00581       return __res;
00582     }
00583 
00584     // Return a bucket count appropriate for n elements
00585     std::size_t
00586     _M_bkt_for_elements(std::size_t __n) const noexcept
00587     { return __builtin_ceil(__n / (long double)_M_max_load_factor); }
00588 
00589     // __n_bkt is current bucket count, __n_elt is current element count,
00590     // and __n_ins is number of elements to be inserted.  Do we need to
00591     // increase bucket count?  If so, return make_pair(true, n), where n
00592     // is the new bucket count.  If not, return make_pair(false, 0).
00593     std::pair<bool, std::size_t>
00594     _M_need_rehash(std::size_t __n_bkt, std::size_t __n_elt,
00595                    std::size_t __n_ins) noexcept
00596     {
00597       if (__n_elt + __n_ins >= _M_next_resize)
00598         {
00599           long double __min_bkts = (__n_elt + __n_ins)
00600                                         / (long double)_M_max_load_factor;
00601           if (__min_bkts >= __n_bkt)
00602             return std::make_pair(true,
00603               _M_next_bkt(std::max<std::size_t>(__builtin_floor(__min_bkts) + 1,
00604                                                 __n_bkt * _S_growth_factor)));
00605 
00606           _M_next_resize
00607             = __builtin_floor(__n_bkt * (long double)_M_max_load_factor);
00608           return std::make_pair(false, 0);
00609         }
00610       else
00611         return std::make_pair(false, 0);
00612     }
00613 
00614     typedef std::size_t _State;
00615 
00616     _State
00617     _M_state() const noexcept
00618     { return _M_next_resize; }
00619 
00620     void
00621     _M_reset() noexcept
00622     { _M_next_resize = 0; }
00623 
00624     void
00625     _M_reset(_State __state) noexcept
00626     { _M_next_resize = __state; }
00627 
00628     static const std::size_t _S_growth_factor = 2;
00629 
00630     float       _M_max_load_factor;
00631     std::size_t _M_next_resize;
00632   };
00633 
00634   // Base classes for std::_Hashtable.  We define these base classes
00635   // because in some cases we want to do different things depending on
00636   // the value of a policy class.  In some cases the policy class
00637   // affects which member functions and nested typedefs are defined;
00638   // we handle that by specializing base class templates.  Several of
00639   // the base class templates need to access other members of class
00640   // template _Hashtable, so we use a variant of the "Curiously
00641   // Recurring Template Pattern" (CRTP) technique.
00642 
00643   /**
00644    *  Primary class template _Map_base.
00645    *
00646    *  If the hashtable has a value type of the form pair<T1, T2> and a
00647    *  key extraction policy (_ExtractKey) that returns the first part
00648    *  of the pair, the hashtable gets a mapped_type typedef.  If it
00649    *  satisfies those criteria and also has unique keys, then it also
00650    *  gets an operator[].
00651    */
00652   template<typename _Key, typename _Value, typename _Alloc,
00653            typename _ExtractKey, typename _Equal,
00654            typename _H1, typename _H2, typename _Hash,
00655            typename _RehashPolicy, typename _Traits,
00656            bool _Unique_keys = _Traits::__unique_keys::value>
00657     struct _Map_base { };
00658 
00659   /// Partial specialization, __unique_keys set to false.
00660   template<typename _Key, typename _Pair, typename _Alloc, typename _Equal,
00661            typename _H1, typename _H2, typename _Hash,
00662            typename _RehashPolicy, typename _Traits>
00663     struct _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal,
00664                      _H1, _H2, _Hash, _RehashPolicy, _Traits, false>
00665     {
00666       using mapped_type = typename std::tuple_element<1, _Pair>::type;
00667     };
00668 
00669   /// Partial specialization, __unique_keys set to true.
00670   template<typename _Key, typename _Pair, typename _Alloc, typename _Equal,
00671            typename _H1, typename _H2, typename _Hash,
00672            typename _RehashPolicy, typename _Traits>
00673     struct _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal,
00674                      _H1, _H2, _Hash, _RehashPolicy, _Traits, true>
00675     {
00676     private:
00677       using __hashtable_base = __detail::_Hashtable_base<_Key, _Pair,
00678                                                          _Select1st,
00679                                                         _Equal, _H1, _H2, _Hash,
00680                                                           _Traits>;
00681 
00682       using __hashtable = _Hashtable<_Key, _Pair, _Alloc,
00683                                      _Select1st, _Equal,
00684                                      _H1, _H2, _Hash, _RehashPolicy, _Traits>;
00685 
00686       using __hash_code = typename __hashtable_base::__hash_code;
00687       using __node_type = typename __hashtable_base::__node_type;
00688 
00689     public:
00690       using key_type = typename __hashtable_base::key_type;
00691       using iterator = typename __hashtable_base::iterator;
00692       using mapped_type = typename std::tuple_element<1, _Pair>::type;
00693 
00694       mapped_type&
00695       operator[](const key_type& __k);
00696 
00697       mapped_type&
00698       operator[](key_type&& __k);
00699 
00700       // _GLIBCXX_RESOLVE_LIB_DEFECTS
00701       // DR 761. unordered_map needs an at() member function.
00702       mapped_type&
00703       at(const key_type& __k);
00704 
00705       const mapped_type&
00706       at(const key_type& __k) const;
00707     };
00708 
00709   template<typename _Key, typename _Pair, typename _Alloc, typename _Equal,
00710            typename _H1, typename _H2, typename _Hash,
00711            typename _RehashPolicy, typename _Traits>
00712     auto
00713     _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal,
00714               _H1, _H2, _Hash, _RehashPolicy, _Traits, true>::
00715     operator[](const key_type& __k)
00716     -> mapped_type&
00717     {
00718       __hashtable* __h = static_cast<__hashtable*>(this);
00719       __hash_code __code = __h->_M_hash_code(__k);
00720       std::size_t __n = __h->_M_bucket_index(__k, __code);
00721       __node_type* __p = __h->_M_find_node(__n, __k, __code);
00722 
00723       if (!__p)
00724         {
00725           __p = __h->_M_allocate_node(std::piecewise_construct,
00726                                       std::tuple<const key_type&>(__k),
00727                                       std::tuple<>());
00728           return __h->_M_insert_unique_node(__n, __code, __p)->second;
00729         }
00730 
00731       return __p->_M_v().second;
00732     }
00733 
00734   template<typename _Key, typename _Pair, typename _Alloc, typename _Equal,
00735            typename _H1, typename _H2, typename _Hash,
00736            typename _RehashPolicy, typename _Traits>
00737     auto
00738     _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal,
00739               _H1, _H2, _Hash, _RehashPolicy, _Traits, true>::
00740     operator[](key_type&& __k)
00741     -> mapped_type&
00742     {
00743       __hashtable* __h = static_cast<__hashtable*>(this);
00744       __hash_code __code = __h->_M_hash_code(__k);
00745       std::size_t __n = __h->_M_bucket_index(__k, __code);
00746       __node_type* __p = __h->_M_find_node(__n, __k, __code);
00747 
00748       if (!__p)
00749         {
00750           __p = __h->_M_allocate_node(std::piecewise_construct,
00751                                       std::forward_as_tuple(std::move(__k)),
00752                                       std::tuple<>());
00753           return __h->_M_insert_unique_node(__n, __code, __p)->second;
00754         }
00755 
00756       return __p->_M_v().second;
00757     }
00758 
00759   template<typename _Key, typename _Pair, typename _Alloc, typename _Equal,
00760            typename _H1, typename _H2, typename _Hash,
00761            typename _RehashPolicy, typename _Traits>
00762     auto
00763     _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal,
00764               _H1, _H2, _Hash, _RehashPolicy, _Traits, true>::
00765     at(const key_type& __k)
00766     -> mapped_type&
00767     {
00768       __hashtable* __h = static_cast<__hashtable*>(this);
00769       __hash_code __code = __h->_M_hash_code(__k);
00770       std::size_t __n = __h->_M_bucket_index(__k, __code);
00771       __node_type* __p = __h->_M_find_node(__n, __k, __code);
00772 
00773       if (!__p)
00774         __throw_out_of_range(__N("_Map_base::at"));
00775       return __p->_M_v().second;
00776     }
00777 
00778   template<typename _Key, typename _Pair, typename _Alloc, typename _Equal,
00779            typename _H1, typename _H2, typename _Hash,
00780            typename _RehashPolicy, typename _Traits>
00781     auto
00782     _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal,
00783               _H1, _H2, _Hash, _RehashPolicy, _Traits, true>::
00784     at(const key_type& __k) const
00785     -> const mapped_type&
00786     {
00787       const __hashtable* __h = static_cast<const __hashtable*>(this);
00788       __hash_code __code = __h->_M_hash_code(__k);
00789       std::size_t __n = __h->_M_bucket_index(__k, __code);
00790       __node_type* __p = __h->_M_find_node(__n, __k, __code);
00791 
00792       if (!__p)
00793         __throw_out_of_range(__N("_Map_base::at"));
00794       return __p->_M_v().second;
00795     }
00796 
00797   /**
00798    *  Primary class template _Insert_base.
00799    *
00800    *  Defines @c insert member functions appropriate to all _Hashtables.
00801    */
00802   template<typename _Key, typename _Value, typename _Alloc,
00803            typename _ExtractKey, typename _Equal,
00804            typename _H1, typename _H2, typename _Hash,
00805            typename _RehashPolicy, typename _Traits>
00806     struct _Insert_base
00807     {
00808     protected:
00809       using __hashtable = _Hashtable<_Key, _Value, _Alloc, _ExtractKey,
00810                                      _Equal, _H1, _H2, _Hash,
00811                                      _RehashPolicy, _Traits>;
00812 
00813       using __hashtable_base = _Hashtable_base<_Key, _Value, _ExtractKey,
00814                                                _Equal, _H1, _H2, _Hash,
00815                                                _Traits>;
00816 
00817       using value_type = typename __hashtable_base::value_type;
00818       using iterator = typename __hashtable_base::iterator;
00819       using const_iterator =  typename __hashtable_base::const_iterator;
00820       using size_type = typename __hashtable_base::size_type;
00821 
00822       using __unique_keys = typename __hashtable_base::__unique_keys;
00823       using __ireturn_type = typename __hashtable_base::__ireturn_type;
00824       using __node_type = _Hash_node<_Value, _Traits::__hash_cached::value>;
00825       using __node_alloc_type = __alloc_rebind<_Alloc, __node_type>;
00826       using __node_gen_type = _AllocNode<__node_alloc_type>;
00827 
00828       __hashtable&
00829       _M_conjure_hashtable()
00830       { return *(static_cast<__hashtable*>(this)); }
00831 
00832       template<typename _InputIterator, typename _NodeGetter>
00833         void
00834         _M_insert_range(_InputIterator __first, _InputIterator __last,
00835                         const _NodeGetter&);
00836 
00837     public:
00838       __ireturn_type
00839       insert(const value_type& __v)
00840       {
00841         __hashtable& __h = _M_conjure_hashtable();
00842         __node_gen_type __node_gen(__h);
00843         return __h._M_insert(__v, __node_gen, __unique_keys());
00844       }
00845 
00846       iterator
00847       insert(const_iterator __hint, const value_type& __v)
00848       {
00849         __hashtable& __h = _M_conjure_hashtable();
00850         __node_gen_type __node_gen(__h);        
00851         return __h._M_insert(__hint, __v, __node_gen, __unique_keys());
00852       }
00853 
00854       void
00855       insert(initializer_list<value_type> __l)
00856       { this->insert(__l.begin(), __l.end()); }
00857 
00858       template<typename _InputIterator>
00859         void
00860         insert(_InputIterator __first, _InputIterator __last)
00861         {
00862           __hashtable& __h = _M_conjure_hashtable();
00863           __node_gen_type __node_gen(__h);
00864           return _M_insert_range(__first, __last, __node_gen);
00865         }
00866     };
00867 
00868   template<typename _Key, typename _Value, typename _Alloc,
00869            typename _ExtractKey, typename _Equal,
00870            typename _H1, typename _H2, typename _Hash,
00871            typename _RehashPolicy, typename _Traits>
00872     template<typename _InputIterator, typename _NodeGetter>
00873       void
00874       _Insert_base<_Key, _Value, _Alloc, _ExtractKey, _Equal, _H1, _H2, _Hash,
00875                     _RehashPolicy, _Traits>::
00876       _M_insert_range(_InputIterator __first, _InputIterator __last,
00877                       const _NodeGetter& __node_gen)
00878       {
00879         using __rehash_type = typename __hashtable::__rehash_type;
00880         using __rehash_state = typename __hashtable::__rehash_state;
00881         using pair_type = std::pair<bool, std::size_t>;
00882 
00883         size_type __n_elt = __detail::__distance_fw(__first, __last);
00884 
00885         __hashtable& __h = _M_conjure_hashtable();
00886         __rehash_type& __rehash = __h._M_rehash_policy;
00887         const __rehash_state& __saved_state = __rehash._M_state();
00888         pair_type __do_rehash = __rehash._M_need_rehash(__h._M_bucket_count,
00889                                                         __h._M_element_count,
00890                                                         __n_elt);
00891 
00892         if (__do_rehash.first)
00893           __h._M_rehash(__do_rehash.second, __saved_state);
00894 
00895         for (; __first != __last; ++__first)
00896           __h._M_insert(*__first, __node_gen, __unique_keys());
00897       }
00898 
00899   /**
00900    *  Primary class template _Insert.
00901    *
00902    *  Defines @c insert member functions that depend on _Hashtable policies,
00903    *  via partial specializations.
00904    */
00905   template<typename _Key, typename _Value, typename _Alloc,
00906            typename _ExtractKey, typename _Equal,
00907            typename _H1, typename _H2, typename _Hash,
00908            typename _RehashPolicy, typename _Traits,
00909            bool _Constant_iterators = _Traits::__constant_iterators::value>
00910     struct _Insert;
00911 
00912   /// Specialization.
00913   template<typename _Key, typename _Value, typename _Alloc,
00914            typename _ExtractKey, typename _Equal,
00915            typename _H1, typename _H2, typename _Hash,
00916            typename _RehashPolicy, typename _Traits>
00917     struct _Insert<_Key, _Value, _Alloc, _ExtractKey, _Equal, _H1, _H2, _Hash,
00918                    _RehashPolicy, _Traits, true>
00919     : public _Insert_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
00920                            _H1, _H2, _Hash, _RehashPolicy, _Traits>
00921     {
00922       using __base_type = _Insert_base<_Key, _Value, _Alloc, _ExtractKey,
00923                                         _Equal, _H1, _H2, _Hash,
00924                                         _RehashPolicy, _Traits>;
00925 
00926       using __hashtable_base = _Hashtable_base<_Key, _Value, _ExtractKey,
00927                                                _Equal, _H1, _H2, _Hash,
00928                                                _Traits>;
00929 
00930       using value_type = typename __base_type::value_type;
00931       using iterator = typename __base_type::iterator;
00932       using const_iterator =  typename __base_type::const_iterator;
00933 
00934       using __unique_keys = typename __base_type::__unique_keys;
00935       using __ireturn_type = typename __hashtable_base::__ireturn_type;
00936       using __hashtable = typename __base_type::__hashtable;
00937       using __node_gen_type = typename __base_type::__node_gen_type;
00938 
00939       using __base_type::insert;
00940 
00941       __ireturn_type
00942       insert(value_type&& __v)
00943       {
00944         __hashtable& __h = this->_M_conjure_hashtable();
00945         __node_gen_type __node_gen(__h);
00946         return __h._M_insert(std::move(__v), __node_gen, __unique_keys());
00947       }
00948 
00949       iterator
00950       insert(const_iterator __hint, value_type&& __v)
00951       {
00952         __hashtable& __h = this->_M_conjure_hashtable();
00953         __node_gen_type __node_gen(__h);
00954         return __h._M_insert(__hint, std::move(__v), __node_gen,
00955                              __unique_keys());
00956       }
00957     };
00958 
00959   /// Specialization.
00960   template<typename _Key, typename _Value, typename _Alloc,
00961            typename _ExtractKey, typename _Equal,
00962            typename _H1, typename _H2, typename _Hash,
00963            typename _RehashPolicy, typename _Traits>
00964     struct _Insert<_Key, _Value, _Alloc, _ExtractKey, _Equal, _H1, _H2, _Hash,
00965                    _RehashPolicy, _Traits, false>
00966     : public _Insert_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
00967                            _H1, _H2, _Hash, _RehashPolicy, _Traits>
00968     {
00969       using __base_type = _Insert_base<_Key, _Value, _Alloc, _ExtractKey,
00970                                        _Equal, _H1, _H2, _Hash,
00971                                        _RehashPolicy, _Traits>;
00972       using value_type = typename __base_type::value_type;
00973       using iterator = typename __base_type::iterator;
00974       using const_iterator =  typename __base_type::const_iterator;
00975 
00976       using __unique_keys = typename __base_type::__unique_keys;
00977       using __hashtable = typename __base_type::__hashtable;
00978       using __ireturn_type = typename __base_type::__ireturn_type;
00979 
00980       using __base_type::insert;
00981 
00982       template<typename _Pair>
00983         using __is_cons = std::is_constructible<value_type, _Pair&&>;
00984 
00985       template<typename _Pair>
00986         using _IFcons = std::enable_if<__is_cons<_Pair>::value>;
00987 
00988       template<typename _Pair>
00989         using _IFconsp = typename _IFcons<_Pair>::type;
00990 
00991       template<typename _Pair, typename = _IFconsp<_Pair>>
00992         __ireturn_type
00993         insert(_Pair&& __v)
00994         {
00995           __hashtable& __h = this->_M_conjure_hashtable();
00996           return __h._M_emplace(__unique_keys(), std::forward<_Pair>(__v));
00997         }
00998 
00999       template<typename _Pair, typename = _IFconsp<_Pair>>
01000         iterator
01001         insert(const_iterator __hint, _Pair&& __v)
01002         {
01003           __hashtable& __h = this->_M_conjure_hashtable();
01004           return __h._M_emplace(__hint, __unique_keys(),
01005                                 std::forward<_Pair>(__v));
01006         }
01007    };
01008 
01009   template<typename _Policy>
01010     using __has_load_factor = typename _Policy::__has_load_factor;
01011 
01012   /**
01013    *  Primary class template  _Rehash_base.
01014    *
01015    *  Give hashtable the max_load_factor functions and reserve iff the
01016    *  rehash policy supports it.
01017   */
01018   template<typename _Key, typename _Value, typename _Alloc,
01019            typename _ExtractKey, typename _Equal,
01020            typename _H1, typename _H2, typename _Hash,
01021            typename _RehashPolicy, typename _Traits,
01022            typename =
01023              __detected_or_t<std::false_type, __has_load_factor, _RehashPolicy>>
01024     struct _Rehash_base;
01025 
01026   /// Specialization when rehash policy doesn't provide load factor management.
01027   template<typename _Key, typename _Value, typename _Alloc,
01028            typename _ExtractKey, typename _Equal,
01029            typename _H1, typename _H2, typename _Hash,
01030            typename _RehashPolicy, typename _Traits>
01031     struct _Rehash_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
01032                       _H1, _H2, _Hash, _RehashPolicy, _Traits,
01033                       std::false_type>
01034     {
01035     };
01036 
01037   /// Specialization when rehash policy provide load factor management.
01038   template<typename _Key, typename _Value, typename _Alloc,
01039            typename _ExtractKey, typename _Equal,
01040            typename _H1, typename _H2, typename _Hash,
01041            typename _RehashPolicy, typename _Traits>
01042     struct _Rehash_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
01043                         _H1, _H2, _Hash, _RehashPolicy, _Traits,
01044                         std::true_type>
01045     {
01046       using __hashtable = _Hashtable<_Key, _Value, _Alloc, _ExtractKey,
01047                                      _Equal, _H1, _H2, _Hash,
01048                                      _RehashPolicy, _Traits>;
01049 
01050       float
01051       max_load_factor() const noexcept
01052       {
01053         const __hashtable* __this = static_cast<const __hashtable*>(this);
01054         return __this->__rehash_policy().max_load_factor();
01055       }
01056 
01057       void
01058       max_load_factor(float __z)
01059       {
01060         __hashtable* __this = static_cast<__hashtable*>(this);
01061         __this->__rehash_policy(_RehashPolicy(__z));
01062       }
01063 
01064       void
01065       reserve(std::size_t __n)
01066       {
01067         __hashtable* __this = static_cast<__hashtable*>(this);
01068         __this->rehash(__builtin_ceil(__n / max_load_factor()));
01069       }
01070     };
01071 
01072   /**
01073    *  Primary class template _Hashtable_ebo_helper.
01074    *
01075    *  Helper class using EBO when it is not forbidden (the type is not
01076    *  final) and when it is worth it (the type is empty.)
01077    */
01078   template<int _Nm, typename _Tp,
01079            bool __use_ebo = !__is_final(_Tp) && __is_empty(_Tp)>
01080     struct _Hashtable_ebo_helper;
01081 
01082   /// Specialization using EBO.
01083   template<int _Nm, typename _Tp>
01084     struct _Hashtable_ebo_helper<_Nm, _Tp, true>
01085     : private _Tp
01086     {
01087       _Hashtable_ebo_helper() = default;
01088 
01089       template<typename _OtherTp>
01090         _Hashtable_ebo_helper(_OtherTp&& __tp)
01091           : _Tp(std::forward<_OtherTp>(__tp))
01092         { }
01093 
01094       static const _Tp&
01095       _S_cget(const _Hashtable_ebo_helper& __eboh)
01096       { return static_cast<const _Tp&>(__eboh); }
01097 
01098       static _Tp&
01099       _S_get(_Hashtable_ebo_helper& __eboh)
01100       { return static_cast<_Tp&>(__eboh); }
01101     };
01102 
01103   /// Specialization not using EBO.
01104   template<int _Nm, typename _Tp>
01105     struct _Hashtable_ebo_helper<_Nm, _Tp, false>
01106     {
01107       _Hashtable_ebo_helper() = default;
01108 
01109       template<typename _OtherTp>
01110         _Hashtable_ebo_helper(_OtherTp&& __tp)
01111           : _M_tp(std::forward<_OtherTp>(__tp))
01112         { }
01113 
01114       static const _Tp&
01115       _S_cget(const _Hashtable_ebo_helper& __eboh)
01116       { return __eboh._M_tp; }
01117 
01118       static _Tp&
01119       _S_get(_Hashtable_ebo_helper& __eboh)
01120       { return __eboh._M_tp; }
01121 
01122     private:
01123       _Tp _M_tp;
01124     };
01125 
01126   /**
01127    *  Primary class template _Local_iterator_base.
01128    *
01129    *  Base class for local iterators, used to iterate within a bucket
01130    *  but not between buckets.
01131    */
01132   template<typename _Key, typename _Value, typename _ExtractKey,
01133            typename _H1, typename _H2, typename _Hash,
01134            bool __cache_hash_code>
01135     struct _Local_iterator_base;
01136 
01137   /**
01138    *  Primary class template _Hash_code_base.
01139    *
01140    *  Encapsulates two policy issues that aren't quite orthogonal.
01141    *   (1) the difference between using a ranged hash function and using
01142    *       the combination of a hash function and a range-hashing function.
01143    *       In the former case we don't have such things as hash codes, so
01144    *       we have a dummy type as placeholder.
01145    *   (2) Whether or not we cache hash codes.  Caching hash codes is
01146    *       meaningless if we have a ranged hash function.
01147    *
01148    *  We also put the key extraction objects here, for convenience.
01149    *  Each specialization derives from one or more of the template
01150    *  parameters to benefit from Ebo. This is important as this type
01151    *  is inherited in some cases by the _Local_iterator_base type used
01152    *  to implement local_iterator and const_local_iterator. As with
01153    *  any iterator type we prefer to make it as small as possible.
01154    *
01155    *  Primary template is unused except as a hook for specializations.
01156    */
01157   template<typename _Key, typename _Value, typename _ExtractKey,
01158            typename _H1, typename _H2, typename _Hash,
01159            bool __cache_hash_code>
01160     struct _Hash_code_base;
01161 
01162   /// Specialization: ranged hash function, no caching hash codes.  H1
01163   /// and H2 are provided but ignored.  We define a dummy hash code type.
01164   template<typename _Key, typename _Value, typename _ExtractKey,
01165            typename _H1, typename _H2, typename _Hash>
01166     struct _Hash_code_base<_Key, _Value, _ExtractKey, _H1, _H2, _Hash, false>
01167     : private _Hashtable_ebo_helper<0, _ExtractKey>,
01168       private _Hashtable_ebo_helper<1, _Hash>
01169     {
01170     private:
01171       using __ebo_extract_key = _Hashtable_ebo_helper<0, _ExtractKey>;
01172       using __ebo_hash = _Hashtable_ebo_helper<1, _Hash>;
01173 
01174     protected:
01175       typedef void*                                     __hash_code;
01176       typedef _Hash_node<_Value, false>                 __node_type;
01177 
01178       // We need the default constructor for the local iterators and _Hashtable
01179       // default constructor.
01180       _Hash_code_base() = default;
01181 
01182       _Hash_code_base(const _ExtractKey& __ex, const _H1&, const _H2&,
01183                       const _Hash& __h)
01184       : __ebo_extract_key(__ex), __ebo_hash(__h) { }
01185 
01186       __hash_code
01187       _M_hash_code(const _Key& __key) const
01188       { return 0; }
01189 
01190       std::size_t
01191       _M_bucket_index(const _Key& __k, __hash_code, std::size_t __n) const
01192       { return _M_ranged_hash()(__k, __n); }
01193 
01194       std::size_t
01195       _M_bucket_index(const __node_type* __p, std::size_t __n) const
01196         noexcept( noexcept(declval<const _Hash&>()(declval<const _Key&>(),
01197                                                    (std::size_t)0)) )
01198       { return _M_ranged_hash()(_M_extract()(__p->_M_v()), __n); }
01199 
01200       void
01201       _M_store_code(__node_type*, __hash_code) const
01202       { }
01203 
01204       void
01205       _M_copy_code(__node_type*, const __node_type*) const
01206       { }
01207 
01208       void
01209       _M_swap(_Hash_code_base& __x)
01210       {
01211         std::swap(_M_extract(), __x._M_extract());
01212         std::swap(_M_ranged_hash(), __x._M_ranged_hash());
01213       }
01214 
01215       const _ExtractKey&
01216       _M_extract() const { return __ebo_extract_key::_S_cget(*this); }
01217 
01218       _ExtractKey&
01219       _M_extract() { return __ebo_extract_key::_S_get(*this); }
01220 
01221       const _Hash&
01222       _M_ranged_hash() const { return __ebo_hash::_S_cget(*this); }
01223 
01224       _Hash&
01225       _M_ranged_hash() { return __ebo_hash::_S_get(*this); }
01226     };
01227 
01228   // No specialization for ranged hash function while caching hash codes.
01229   // That combination is meaningless, and trying to do it is an error.
01230 
01231   /// Specialization: ranged hash function, cache hash codes.  This
01232   /// combination is meaningless, so we provide only a declaration
01233   /// and no definition.
01234   template<typename _Key, typename _Value, typename _ExtractKey,
01235            typename _H1, typename _H2, typename _Hash>
01236     struct _Hash_code_base<_Key, _Value, _ExtractKey, _H1, _H2, _Hash, true>;
01237 
01238   /// Specialization: hash function and range-hashing function, no
01239   /// caching of hash codes.
01240   /// Provides typedef and accessor required by C++ 11.
01241   template<typename _Key, typename _Value, typename _ExtractKey,
01242            typename _H1, typename _H2>
01243     struct _Hash_code_base<_Key, _Value, _ExtractKey, _H1, _H2,
01244                            _Default_ranged_hash, false>
01245     : private _Hashtable_ebo_helper<0, _ExtractKey>,
01246       private _Hashtable_ebo_helper<1, _H1>,
01247       private _Hashtable_ebo_helper<2, _H2>
01248     {
01249     private:
01250       using __ebo_extract_key = _Hashtable_ebo_helper<0, _ExtractKey>;
01251       using __ebo_h1 = _Hashtable_ebo_helper<1, _H1>;
01252       using __ebo_h2 = _Hashtable_ebo_helper<2, _H2>;
01253 
01254       // Gives the local iterator implementation access to _M_bucket_index().
01255       friend struct _Local_iterator_base<_Key, _Value, _ExtractKey, _H1, _H2,
01256                                          _Default_ranged_hash, false>;
01257 
01258     public:
01259       typedef _H1                                       hasher;
01260 
01261       hasher
01262       hash_function() const
01263       { return _M_h1(); }
01264 
01265     protected:
01266       typedef std::size_t                               __hash_code;
01267       typedef _Hash_node<_Value, false>                 __node_type;
01268 
01269       // We need the default constructor for the local iterators and _Hashtable
01270       // default constructor.
01271       _Hash_code_base() = default;
01272 
01273       _Hash_code_base(const _ExtractKey& __ex,
01274                       const _H1& __h1, const _H2& __h2,
01275                       const _Default_ranged_hash&)
01276       : __ebo_extract_key(__ex), __ebo_h1(__h1), __ebo_h2(__h2) { }
01277 
01278       __hash_code
01279       _M_hash_code(const _Key& __k) const
01280       { return _M_h1()(__k); }
01281 
01282       std::size_t
01283       _M_bucket_index(const _Key&, __hash_code __c, std::size_t __n) const
01284       { return _M_h2()(__c, __n); }
01285 
01286       std::size_t
01287       _M_bucket_index(const __node_type* __p, std::size_t __n) const
01288         noexcept( noexcept(declval<const _H1&>()(declval<const _Key&>()))
01289                   && noexcept(declval<const _H2&>()((__hash_code)0,
01290                                                     (std::size_t)0)) )
01291       { return _M_h2()(_M_h1()(_M_extract()(__p->_M_v())), __n); }
01292 
01293       void
01294       _M_store_code(__node_type*, __hash_code) const
01295       { }
01296 
01297       void
01298       _M_copy_code(__node_type*, const __node_type*) const
01299       { }
01300 
01301       void
01302       _M_swap(_Hash_code_base& __x)
01303       {
01304         std::swap(_M_extract(), __x._M_extract());
01305         std::swap(_M_h1(), __x._M_h1());
01306         std::swap(_M_h2(), __x._M_h2());
01307       }
01308 
01309       const _ExtractKey&
01310       _M_extract() const { return __ebo_extract_key::_S_cget(*this); }
01311 
01312       _ExtractKey&
01313       _M_extract() { return __ebo_extract_key::_S_get(*this); }
01314 
01315       const _H1&
01316       _M_h1() const { return __ebo_h1::_S_cget(*this); }
01317 
01318       _H1&
01319       _M_h1() { return __ebo_h1::_S_get(*this); }
01320 
01321       const _H2&
01322       _M_h2() const { return __ebo_h2::_S_cget(*this); }
01323 
01324       _H2&
01325       _M_h2() { return __ebo_h2::_S_get(*this); }
01326     };
01327 
01328   /// Specialization: hash function and range-hashing function,
01329   /// caching hash codes.  H is provided but ignored.  Provides
01330   /// typedef and accessor required by C++ 11.
01331   template<typename _Key, typename _Value, typename _ExtractKey,
01332            typename _H1, typename _H2>
01333     struct _Hash_code_base<_Key, _Value, _ExtractKey, _H1, _H2,
01334                            _Default_ranged_hash, true>
01335     : private _Hashtable_ebo_helper<0, _ExtractKey>,
01336       private _Hashtable_ebo_helper<1, _H1>,
01337       private _Hashtable_ebo_helper<2, _H2>
01338     {
01339     private:
01340       // Gives the local iterator implementation access to _M_h2().
01341       friend struct _Local_iterator_base<_Key, _Value, _ExtractKey, _H1, _H2,
01342                                          _Default_ranged_hash, true>;
01343 
01344       using __ebo_extract_key = _Hashtable_ebo_helper<0, _ExtractKey>;
01345       using __ebo_h1 = _Hashtable_ebo_helper<1, _H1>;
01346       using __ebo_h2 = _Hashtable_ebo_helper<2, _H2>;
01347 
01348     public:
01349       typedef _H1                                       hasher;
01350 
01351       hasher
01352       hash_function() const
01353       { return _M_h1(); }
01354 
01355     protected:
01356       typedef std::size_t                               __hash_code;
01357       typedef _Hash_node<_Value, true>                  __node_type;
01358 
01359       // We need the default constructor for _Hashtable default constructor.
01360       _Hash_code_base() = default;
01361       _Hash_code_base(const _ExtractKey& __ex,
01362                       const _H1& __h1, const _H2& __h2,
01363                       const _Default_ranged_hash&)
01364       : __ebo_extract_key(__ex), __ebo_h1(__h1), __ebo_h2(__h2) { }
01365 
01366       __hash_code
01367       _M_hash_code(const _Key& __k) const
01368       { return _M_h1()(__k); }
01369 
01370       std::size_t
01371       _M_bucket_index(const _Key&, __hash_code __c,
01372                       std::size_t __n) const
01373       { return _M_h2()(__c, __n); }
01374 
01375       std::size_t
01376       _M_bucket_index(const __node_type* __p, std::size_t __n) const
01377         noexcept( noexcept(declval<const _H2&>()((__hash_code)0,
01378                                                  (std::size_t)0)) )
01379       { return _M_h2()(__p->_M_hash_code, __n); }
01380 
01381       void
01382       _M_store_code(__node_type* __n, __hash_code __c) const
01383       { __n->_M_hash_code = __c; }
01384 
01385       void
01386       _M_copy_code(__node_type* __to, const __node_type* __from) const
01387       { __to->_M_hash_code = __from->_M_hash_code; }
01388 
01389       void
01390       _M_swap(_Hash_code_base& __x)
01391       {
01392         std::swap(_M_extract(), __x._M_extract());
01393         std::swap(_M_h1(), __x._M_h1());
01394         std::swap(_M_h2(), __x._M_h2());
01395       }
01396 
01397       const _ExtractKey&
01398       _M_extract() const { return __ebo_extract_key::_S_cget(*this); }
01399 
01400       _ExtractKey&
01401       _M_extract() { return __ebo_extract_key::_S_get(*this); }
01402 
01403       const _H1&
01404       _M_h1() const { return __ebo_h1::_S_cget(*this); }
01405 
01406       _H1&
01407       _M_h1() { return __ebo_h1::_S_get(*this); }
01408 
01409       const _H2&
01410       _M_h2() const { return __ebo_h2::_S_cget(*this); }
01411 
01412       _H2&
01413       _M_h2() { return __ebo_h2::_S_get(*this); }
01414     };
01415 
01416   /**
01417    *  Primary class template _Equal_helper.
01418    *
01419    */
01420   template <typename _Key, typename _Value, typename _ExtractKey,
01421             typename _Equal, typename _HashCodeType,
01422             bool __cache_hash_code>
01423   struct _Equal_helper;
01424 
01425   /// Specialization.
01426   template<typename _Key, typename _Value, typename _ExtractKey,
01427            typename _Equal, typename _HashCodeType>
01428   struct _Equal_helper<_Key, _Value, _ExtractKey, _Equal, _HashCodeType, true>
01429   {
01430     static bool
01431     _S_equals(const _Equal& __eq, const _ExtractKey& __extract,
01432               const _Key& __k, _HashCodeType __c, _Hash_node<_Value, true>* __n)
01433     { return __c == __n->_M_hash_code && __eq(__k, __extract(__n->_M_v())); }
01434   };
01435 
01436   /// Specialization.
01437   template<typename _Key, typename _Value, typename _ExtractKey,
01438            typename _Equal, typename _HashCodeType>
01439   struct _Equal_helper<_Key, _Value, _ExtractKey, _Equal, _HashCodeType, false>
01440   {
01441     static bool
01442     _S_equals(const _Equal& __eq, const _ExtractKey& __extract,
01443               const _Key& __k, _HashCodeType, _Hash_node<_Value, false>* __n)
01444     { return __eq(__k, __extract(__n->_M_v())); }
01445   };
01446 
01447 
01448   /// Partial specialization used when nodes contain a cached hash code.
01449   template<typename _Key, typename _Value, typename _ExtractKey,
01450            typename _H1, typename _H2, typename _Hash>
01451     struct _Local_iterator_base<_Key, _Value, _ExtractKey,
01452                                 _H1, _H2, _Hash, true>
01453     : private _Hashtable_ebo_helper<0, _H2>
01454     {
01455     protected:
01456       using __base_type = _Hashtable_ebo_helper<0, _H2>;
01457       using __hash_code_base = _Hash_code_base<_Key, _Value, _ExtractKey,
01458                                                _H1, _H2, _Hash, true>;
01459 
01460       _Local_iterator_base() = default;
01461       _Local_iterator_base(const __hash_code_base& __base,
01462                            _Hash_node<_Value, true>* __p,
01463                            std::size_t __bkt, std::size_t __bkt_count)
01464       : __base_type(__base._M_h2()),
01465         _M_cur(__p), _M_bucket(__bkt), _M_bucket_count(__bkt_count) { }
01466 
01467       void
01468       _M_incr()
01469       {
01470         _M_cur = _M_cur->_M_next();
01471         if (_M_cur)
01472           {
01473             std::size_t __bkt
01474               = __base_type::_S_get(*this)(_M_cur->_M_hash_code,
01475                                            _M_bucket_count);
01476             if (__bkt != _M_bucket)
01477               _M_cur = nullptr;
01478           }
01479       }
01480 
01481       _Hash_node<_Value, true>*  _M_cur;
01482       std::size_t _M_bucket;
01483       std::size_t _M_bucket_count;
01484 
01485     public:
01486       const void*
01487       _M_curr() const { return _M_cur; }  // for equality ops
01488 
01489       std::size_t
01490       _M_get_bucket() const { return _M_bucket; }  // for debug mode
01491     };
01492 
01493   // Uninitialized storage for a _Hash_code_base.
01494   // This type is DefaultConstructible and Assignable even if the
01495   // _Hash_code_base type isn't, so that _Local_iterator_base<..., false>
01496   // can be DefaultConstructible and Assignable.
01497   template<typename _Tp, bool _IsEmpty = std::is_empty<_Tp>::value>
01498     struct _Hash_code_storage
01499     {
01500       __gnu_cxx::__aligned_buffer<_Tp> _M_storage;
01501 
01502       _Tp*
01503       _M_h() { return _M_storage._M_ptr(); }
01504 
01505       const _Tp*
01506       _M_h() const { return _M_storage._M_ptr(); }
01507     };
01508 
01509   // Empty partial specialization for empty _Hash_code_base types.
01510   template<typename _Tp>
01511     struct _Hash_code_storage<_Tp, true>
01512     {
01513       static_assert( std::is_empty<_Tp>::value, "Type must be empty" );
01514 
01515       // As _Tp is an empty type there will be no bytes written/read through
01516       // the cast pointer, so no strict-aliasing violation.
01517       _Tp*
01518       _M_h() { return reinterpret_cast<_Tp*>(this); }
01519 
01520       const _Tp*
01521       _M_h() const { return reinterpret_cast<const _Tp*>(this); }
01522     };
01523 
01524   template<typename _Key, typename _Value, typename _ExtractKey,
01525            typename _H1, typename _H2, typename _Hash>
01526     using __hash_code_for_local_iter
01527       = _Hash_code_storage<_Hash_code_base<_Key, _Value, _ExtractKey,
01528                                            _H1, _H2, _Hash, false>>;
01529 
01530   // Partial specialization used when hash codes are not cached
01531   template<typename _Key, typename _Value, typename _ExtractKey,
01532            typename _H1, typename _H2, typename _Hash>
01533     struct _Local_iterator_base<_Key, _Value, _ExtractKey,
01534                                 _H1, _H2, _Hash, false>
01535     : __hash_code_for_local_iter<_Key, _Value, _ExtractKey, _H1, _H2, _Hash>
01536     {
01537     protected:
01538       using __hash_code_base = _Hash_code_base<_Key, _Value, _ExtractKey,
01539                                                _H1, _H2, _Hash, false>;
01540 
01541       _Local_iterator_base() : _M_bucket_count(-1) { }
01542 
01543       _Local_iterator_base(const __hash_code_base& __base,
01544                            _Hash_node<_Value, false>* __p,
01545                            std::size_t __bkt, std::size_t __bkt_count)
01546       : _M_cur(__p), _M_bucket(__bkt), _M_bucket_count(__bkt_count)
01547       { _M_init(__base); }
01548 
01549       ~_Local_iterator_base()
01550       {
01551         if (_M_bucket_count != -1)
01552           _M_destroy();
01553       }
01554 
01555       _Local_iterator_base(const _Local_iterator_base& __iter)
01556       : _M_cur(__iter._M_cur), _M_bucket(__iter._M_bucket),
01557         _M_bucket_count(__iter._M_bucket_count)
01558       {
01559         if (_M_bucket_count != -1)
01560           _M_init(*__iter._M_h());
01561       }
01562 
01563       _Local_iterator_base&
01564       operator=(const _Local_iterator_base& __iter)
01565       {
01566         if (_M_bucket_count != -1)
01567           _M_destroy();
01568         _M_cur = __iter._M_cur;
01569         _M_bucket = __iter._M_bucket;
01570         _M_bucket_count = __iter._M_bucket_count;
01571         if (_M_bucket_count != -1)
01572           _M_init(*__iter._M_h());
01573         return *this;
01574       }
01575 
01576       void
01577       _M_incr()
01578       {
01579         _M_cur = _M_cur->_M_next();
01580         if (_M_cur)
01581           {
01582             std::size_t __bkt = this->_M_h()->_M_bucket_index(_M_cur,
01583                                                               _M_bucket_count);
01584             if (__bkt != _M_bucket)
01585               _M_cur = nullptr;
01586           }
01587       }
01588 
01589       _Hash_node<_Value, false>*  _M_cur;
01590       std::size_t _M_bucket;
01591       std::size_t _M_bucket_count;
01592 
01593       void
01594       _M_init(const __hash_code_base& __base)
01595       { ::new(this->_M_h()) __hash_code_base(__base); }
01596 
01597       void
01598       _M_destroy() { this->_M_h()->~__hash_code_base(); }
01599 
01600     public:
01601       const void*
01602       _M_curr() const { return _M_cur; }  // for equality ops and debug mode
01603 
01604       std::size_t
01605       _M_get_bucket() const { return _M_bucket; }  // for debug mode
01606     };
01607 
01608   template<typename _Key, typename _Value, typename _ExtractKey,
01609            typename _H1, typename _H2, typename _Hash, bool __cache>
01610     inline bool
01611     operator==(const _Local_iterator_base<_Key, _Value, _ExtractKey,
01612                                           _H1, _H2, _Hash, __cache>& __x,
01613                const _Local_iterator_base<_Key, _Value, _ExtractKey,
01614                                           _H1, _H2, _Hash, __cache>& __y)
01615     { return __x._M_curr() == __y._M_curr(); }
01616 
01617   template<typename _Key, typename _Value, typename _ExtractKey,
01618            typename _H1, typename _H2, typename _Hash, bool __cache>
01619     inline bool
01620     operator!=(const _Local_iterator_base<_Key, _Value, _ExtractKey,
01621                                           _H1, _H2, _Hash, __cache>& __x,
01622                const _Local_iterator_base<_Key, _Value, _ExtractKey,
01623                                           _H1, _H2, _Hash, __cache>& __y)
01624     { return __x._M_curr() != __y._M_curr(); }
01625 
01626   /// local iterators
01627   template<typename _Key, typename _Value, typename _ExtractKey,
01628            typename _H1, typename _H2, typename _Hash,
01629            bool __constant_iterators, bool __cache>
01630     struct _Local_iterator
01631     : public _Local_iterator_base<_Key, _Value, _ExtractKey,
01632                                   _H1, _H2, _Hash, __cache>
01633     {
01634     private:
01635       using __base_type = _Local_iterator_base<_Key, _Value, _ExtractKey,
01636                                                _H1, _H2, _Hash, __cache>;
01637       using __hash_code_base = typename __base_type::__hash_code_base;
01638     public:
01639       typedef _Value                                    value_type;
01640       typedef typename std::conditional<__constant_iterators,
01641                                         const _Value*, _Value*>::type
01642                                                        pointer;
01643       typedef typename std::conditional<__constant_iterators,
01644                                         const _Value&, _Value&>::type
01645                                                        reference;
01646       typedef std::ptrdiff_t                            difference_type;
01647       typedef std::forward_iterator_tag                 iterator_category;
01648 
01649       _Local_iterator() = default;
01650 
01651       _Local_iterator(const __hash_code_base& __base,
01652                       _Hash_node<_Value, __cache>* __p,
01653                       std::size_t __bkt, std::size_t __bkt_count)
01654         : __base_type(__base, __p, __bkt, __bkt_count)
01655       { }
01656 
01657       reference
01658       operator*() const
01659       { return this->_M_cur->_M_v(); }
01660 
01661       pointer
01662       operator->() const
01663       { return this->_M_cur->_M_valptr(); }
01664 
01665       _Local_iterator&
01666       operator++()
01667       {
01668         this->_M_incr();
01669         return *this;
01670       }
01671 
01672       _Local_iterator
01673       operator++(int)
01674       {
01675         _Local_iterator __tmp(*this);
01676         this->_M_incr();
01677         return __tmp;
01678       }
01679     };
01680 
01681   /// local const_iterators
01682   template<typename _Key, typename _Value, typename _ExtractKey,
01683            typename _H1, typename _H2, typename _Hash,
01684            bool __constant_iterators, bool __cache>
01685     struct _Local_const_iterator
01686     : public _Local_iterator_base<_Key, _Value, _ExtractKey,
01687                                   _H1, _H2, _Hash, __cache>
01688     {
01689     private:
01690       using __base_type = _Local_iterator_base<_Key, _Value, _ExtractKey,
01691                                                _H1, _H2, _Hash, __cache>;
01692       using __hash_code_base = typename __base_type::__hash_code_base;
01693 
01694     public:
01695       typedef _Value                                    value_type;
01696       typedef const _Value*                             pointer;
01697       typedef const _Value&                             reference;
01698       typedef std::ptrdiff_t                            difference_type;
01699       typedef std::forward_iterator_tag                 iterator_category;
01700 
01701       _Local_const_iterator() = default;
01702 
01703       _Local_const_iterator(const __hash_code_base& __base,
01704                             _Hash_node<_Value, __cache>* __p,
01705                             std::size_t __bkt, std::size_t __bkt_count)
01706         : __base_type(__base, __p, __bkt, __bkt_count)
01707       { }
01708 
01709       _Local_const_iterator(const _Local_iterator<_Key, _Value, _ExtractKey,
01710                                                   _H1, _H2, _Hash,
01711                                                   __constant_iterators,
01712                                                   __cache>& __x)
01713         : __base_type(__x)
01714       { }
01715 
01716       reference
01717       operator*() const
01718       { return this->_M_cur->_M_v(); }
01719 
01720       pointer
01721       operator->() const
01722       { return this->_M_cur->_M_valptr(); }
01723 
01724       _Local_const_iterator&
01725       operator++()
01726       {
01727         this->_M_incr();
01728         return *this;
01729       }
01730 
01731       _Local_const_iterator
01732       operator++(int)
01733       {
01734         _Local_const_iterator __tmp(*this);
01735         this->_M_incr();
01736         return __tmp;
01737       }
01738     };
01739 
01740   /**
01741    *  Primary class template _Hashtable_base.
01742    *
01743    *  Helper class adding management of _Equal functor to
01744    *  _Hash_code_base type.
01745    *
01746    *  Base class templates are:
01747    *    - __detail::_Hash_code_base
01748    *    - __detail::_Hashtable_ebo_helper
01749    */
01750   template<typename _Key, typename _Value,
01751            typename _ExtractKey, typename _Equal,
01752            typename _H1, typename _H2, typename _Hash, typename _Traits>
01753   struct _Hashtable_base
01754   : public _Hash_code_base<_Key, _Value, _ExtractKey, _H1, _H2, _Hash,
01755                            _Traits::__hash_cached::value>,
01756     private _Hashtable_ebo_helper<0, _Equal>
01757   {
01758   public:
01759     typedef _Key                                        key_type;
01760     typedef _Value                                      value_type;
01761     typedef _Equal                                      key_equal;
01762     typedef std::size_t                                 size_type;
01763     typedef std::ptrdiff_t                              difference_type;
01764 
01765     using __traits_type = _Traits;
01766     using __hash_cached = typename __traits_type::__hash_cached;
01767     using __constant_iterators = typename __traits_type::__constant_iterators;
01768     using __unique_keys = typename __traits_type::__unique_keys;
01769 
01770     using __hash_code_base = _Hash_code_base<_Key, _Value, _ExtractKey,
01771                                              _H1, _H2, _Hash,
01772                                              __hash_cached::value>;
01773 
01774     using __hash_code = typename __hash_code_base::__hash_code;
01775     using __node_type = typename __hash_code_base::__node_type;
01776 
01777     using iterator = __detail::_Node_iterator<value_type,
01778                                               __constant_iterators::value,
01779                                               __hash_cached::value>;
01780 
01781     using const_iterator = __detail::_Node_const_iterator<value_type,
01782                                                    __constant_iterators::value,
01783                                                    __hash_cached::value>;
01784 
01785     using local_iterator = __detail::_Local_iterator<key_type, value_type,
01786                                                   _ExtractKey, _H1, _H2, _Hash,
01787                                                   __constant_iterators::value,
01788                                                      __hash_cached::value>;
01789 
01790     using const_local_iterator = __detail::_Local_const_iterator<key_type,
01791                                                                  value_type,
01792                                         _ExtractKey, _H1, _H2, _Hash,
01793                                         __constant_iterators::value,
01794                                         __hash_cached::value>;
01795 
01796     using __ireturn_type = typename std::conditional<__unique_keys::value,
01797                                                      std::pair<iterator, bool>,
01798                                                      iterator>::type;
01799   private:
01800     using _EqualEBO = _Hashtable_ebo_helper<0, _Equal>;
01801     using _EqualHelper =  _Equal_helper<_Key, _Value, _ExtractKey, _Equal,
01802                                         __hash_code, __hash_cached::value>;
01803 
01804   protected:
01805     _Hashtable_base() = default;
01806     _Hashtable_base(const _ExtractKey& __ex, const _H1& __h1, const _H2& __h2,
01807                     const _Hash& __hash, const _Equal& __eq)
01808     : __hash_code_base(__ex, __h1, __h2, __hash), _EqualEBO(__eq)
01809     { }
01810 
01811     bool
01812     _M_equals(const _Key& __k, __hash_code __c, __node_type* __n) const
01813     {
01814       return _EqualHelper::_S_equals(_M_eq(), this->_M_extract(),
01815                                      __k, __c, __n);
01816     }
01817 
01818     void
01819     _M_swap(_Hashtable_base& __x)
01820     {
01821       __hash_code_base::_M_swap(__x);
01822       std::swap(_M_eq(), __x._M_eq());
01823     }
01824 
01825     const _Equal&
01826     _M_eq() const { return _EqualEBO::_S_cget(*this); }
01827 
01828     _Equal&
01829     _M_eq() { return _EqualEBO::_S_get(*this); }
01830   };
01831 
01832   /**
01833    *  struct _Equality_base.
01834    *
01835    *  Common types and functions for class _Equality.
01836    */
01837   struct _Equality_base
01838   {
01839   protected:
01840     template<typename _Uiterator>
01841       static bool
01842       _S_is_permutation(_Uiterator, _Uiterator, _Uiterator);
01843   };
01844 
01845   // See std::is_permutation in N3068.
01846   template<typename _Uiterator>
01847     bool
01848     _Equality_base::
01849     _S_is_permutation(_Uiterator __first1, _Uiterator __last1,
01850                       _Uiterator __first2)
01851     {
01852       for (; __first1 != __last1; ++__first1, ++__first2)
01853         if (!(*__first1 == *__first2))
01854           break;
01855 
01856       if (__first1 == __last1)
01857         return true;
01858 
01859       _Uiterator __last2 = __first2;
01860       std::advance(__last2, std::distance(__first1, __last1));
01861 
01862       for (_Uiterator __it1 = __first1; __it1 != __last1; ++__it1)
01863         {
01864           _Uiterator __tmp =  __first1;
01865           while (__tmp != __it1 && !bool(*__tmp == *__it1))
01866             ++__tmp;
01867 
01868           // We've seen this one before.
01869           if (__tmp != __it1)
01870             continue;
01871 
01872           std::ptrdiff_t __n2 = 0;
01873           for (__tmp = __first2; __tmp != __last2; ++__tmp)
01874             if (*__tmp == *__it1)
01875               ++__n2;
01876 
01877           if (!__n2)
01878             return false;
01879 
01880           std::ptrdiff_t __n1 = 0;
01881           for (__tmp = __it1; __tmp != __last1; ++__tmp)
01882             if (*__tmp == *__it1)
01883               ++__n1;
01884 
01885           if (__n1 != __n2)
01886             return false;
01887         }
01888       return true;
01889     }
01890 
01891   /**
01892    *  Primary class template  _Equality.
01893    *
01894    *  This is for implementing equality comparison for unordered
01895    *  containers, per N3068, by John Lakos and Pablo Halpern.
01896    *  Algorithmically, we follow closely the reference implementations
01897    *  therein.
01898    */
01899   template<typename _Key, typename _Value, typename _Alloc,
01900            typename _ExtractKey, typename _Equal,
01901            typename _H1, typename _H2, typename _Hash,
01902            typename _RehashPolicy, typename _Traits,
01903            bool _Unique_keys = _Traits::__unique_keys::value>
01904     struct _Equality;
01905 
01906   /// Specialization.
01907   template<typename _Key, typename _Value, typename _Alloc,
01908            typename _ExtractKey, typename _Equal,
01909            typename _H1, typename _H2, typename _Hash,
01910            typename _RehashPolicy, typename _Traits>
01911     struct _Equality<_Key, _Value, _Alloc, _ExtractKey, _Equal,
01912                      _H1, _H2, _Hash, _RehashPolicy, _Traits, true>
01913     {
01914       using __hashtable = _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
01915                                      _H1, _H2, _Hash, _RehashPolicy, _Traits>;
01916 
01917       bool
01918       _M_equal(const __hashtable&) const;
01919     };
01920 
01921   template<typename _Key, typename _Value, typename _Alloc,
01922            typename _ExtractKey, typename _Equal,
01923            typename _H1, typename _H2, typename _Hash,
01924            typename _RehashPolicy, typename _Traits>
01925     bool
01926     _Equality<_Key, _Value, _Alloc, _ExtractKey, _Equal,
01927               _H1, _H2, _Hash, _RehashPolicy, _Traits, true>::
01928     _M_equal(const __hashtable& __other) const
01929     {
01930       const __hashtable* __this = static_cast<const __hashtable*>(this);
01931 
01932       if (__this->size() != __other.size())
01933         return false;
01934 
01935       for (auto __itx = __this->begin(); __itx != __this->end(); ++__itx)
01936         {
01937           const auto __ity = __other.find(_ExtractKey()(*__itx));
01938           if (__ity == __other.end() || !bool(*__ity == *__itx))
01939             return false;
01940         }
01941       return true;
01942     }
01943 
01944   /// Specialization.
01945   template<typename _Key, typename _Value, typename _Alloc,
01946            typename _ExtractKey, typename _Equal,
01947            typename _H1, typename _H2, typename _Hash,
01948            typename _RehashPolicy, typename _Traits>
01949     struct _Equality<_Key, _Value, _Alloc, _ExtractKey, _Equal,
01950                      _H1, _H2, _Hash, _RehashPolicy, _Traits, false>
01951     : public _Equality_base
01952     {
01953       using __hashtable = _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
01954                                      _H1, _H2, _Hash, _RehashPolicy, _Traits>;
01955 
01956       bool
01957       _M_equal(const __hashtable&) const;
01958     };
01959 
01960   template<typename _Key, typename _Value, typename _Alloc,
01961            typename _ExtractKey, typename _Equal,
01962            typename _H1, typename _H2, typename _Hash,
01963            typename _RehashPolicy, typename _Traits>
01964     bool
01965     _Equality<_Key, _Value, _Alloc, _ExtractKey, _Equal,
01966               _H1, _H2, _Hash, _RehashPolicy, _Traits, false>::
01967     _M_equal(const __hashtable& __other) const
01968     {
01969       const __hashtable* __this = static_cast<const __hashtable*>(this);
01970 
01971       if (__this->size() != __other.size())
01972         return false;
01973 
01974       for (auto __itx = __this->begin(); __itx != __this->end();)
01975         {
01976           const auto __xrange = __this->equal_range(_ExtractKey()(*__itx));
01977           const auto __yrange = __other.equal_range(_ExtractKey()(*__itx));
01978 
01979           if (std::distance(__xrange.first, __xrange.second)
01980               != std::distance(__yrange.first, __yrange.second))
01981             return false;
01982 
01983           if (!_S_is_permutation(__xrange.first, __xrange.second,
01984                                  __yrange.first))
01985             return false;
01986 
01987           __itx = __xrange.second;
01988         }
01989       return true;
01990     }
01991 
01992   /**
01993    * This type deals with all allocation and keeps an allocator instance through
01994    * inheritance to benefit from EBO when possible.
01995    */
01996   template<typename _NodeAlloc>
01997     struct _Hashtable_alloc : private _Hashtable_ebo_helper<0, _NodeAlloc>
01998     {
01999     private:
02000       using __ebo_node_alloc = _Hashtable_ebo_helper<0, _NodeAlloc>;
02001     public:
02002       using __node_type = typename _NodeAlloc::value_type;
02003       using __node_alloc_type = _NodeAlloc;
02004       // Use __gnu_cxx to benefit from _S_always_equal and al.
02005       using __node_alloc_traits = __gnu_cxx::__alloc_traits<__node_alloc_type>;
02006 
02007       using __value_type = typename __node_type::value_type;
02008       using __value_alloc_type =
02009         __alloc_rebind<__node_alloc_type, __value_type>;
02010       using __value_alloc_traits = std::allocator_traits<__value_alloc_type>;
02011 
02012       using __node_base = __detail::_Hash_node_base;
02013       using __bucket_type = __node_base*;      
02014       using __bucket_alloc_type =
02015         __alloc_rebind<__node_alloc_type, __bucket_type>;
02016       using __bucket_alloc_traits = std::allocator_traits<__bucket_alloc_type>;
02017 
02018       _Hashtable_alloc() = default;
02019       _Hashtable_alloc(const _Hashtable_alloc&) = default;
02020       _Hashtable_alloc(_Hashtable_alloc&&) = default;
02021 
02022       template<typename _Alloc>
02023         _Hashtable_alloc(_Alloc&& __a)
02024           : __ebo_node_alloc(std::forward<_Alloc>(__a))
02025         { }
02026 
02027       __node_alloc_type&
02028       _M_node_allocator()
02029       { return __ebo_node_alloc::_S_get(*this); }
02030 
02031       const __node_alloc_type&
02032       _M_node_allocator() const
02033       { return __ebo_node_alloc::_S_cget(*this); }
02034 
02035       template<typename... _Args>
02036         __node_type*
02037         _M_allocate_node(_Args&&... __args);
02038 
02039       void
02040       _M_deallocate_node(__node_type* __n);
02041 
02042       // Deallocate the linked list of nodes pointed to by __n
02043       void
02044       _M_deallocate_nodes(__node_type* __n);
02045 
02046       __bucket_type*
02047       _M_allocate_buckets(std::size_t __n);
02048 
02049       void
02050       _M_deallocate_buckets(__bucket_type*, std::size_t __n);
02051     };
02052 
02053   // Definitions of class template _Hashtable_alloc's out-of-line member
02054   // functions.
02055   template<typename _NodeAlloc>
02056     template<typename... _Args>
02057       typename _Hashtable_alloc<_NodeAlloc>::__node_type*
02058       _Hashtable_alloc<_NodeAlloc>::_M_allocate_node(_Args&&... __args)
02059       {
02060         auto __nptr = __node_alloc_traits::allocate(_M_node_allocator(), 1);
02061         __node_type* __n = std::__addressof(*__nptr);
02062         __try
02063           {
02064             __value_alloc_type __a(_M_node_allocator());
02065             ::new ((void*)__n) __node_type;
02066             __value_alloc_traits::construct(__a, __n->_M_valptr(),
02067                                             std::forward<_Args>(__args)...);
02068             return __n;
02069           }
02070         __catch(...)
02071           {
02072             __node_alloc_traits::deallocate(_M_node_allocator(), __nptr, 1);
02073             __throw_exception_again;
02074           }
02075       }
02076 
02077   template<typename _NodeAlloc>
02078     void
02079     _Hashtable_alloc<_NodeAlloc>::_M_deallocate_node(__node_type* __n)
02080     {
02081       typedef typename __node_alloc_traits::pointer _Ptr;
02082       auto __ptr = std::pointer_traits<_Ptr>::pointer_to(*__n);
02083       __value_alloc_type __a(_M_node_allocator());
02084       __value_alloc_traits::destroy(__a, __n->_M_valptr());
02085       __n->~__node_type();
02086       __node_alloc_traits::deallocate(_M_node_allocator(), __ptr, 1);
02087     }
02088 
02089   template<typename _NodeAlloc>
02090     void
02091     _Hashtable_alloc<_NodeAlloc>::_M_deallocate_nodes(__node_type* __n)
02092     {
02093       while (__n)
02094         {
02095           __node_type* __tmp = __n;
02096           __n = __n->_M_next();
02097           _M_deallocate_node(__tmp);
02098         }
02099     }
02100 
02101   template<typename _NodeAlloc>
02102     typename _Hashtable_alloc<_NodeAlloc>::__bucket_type*
02103     _Hashtable_alloc<_NodeAlloc>::_M_allocate_buckets(std::size_t __n)
02104     {
02105       __bucket_alloc_type __alloc(_M_node_allocator());
02106 
02107       auto __ptr = __bucket_alloc_traits::allocate(__alloc, __n);
02108       __bucket_type* __p = std::__addressof(*__ptr);
02109       __builtin_memset(__p, 0, __n * sizeof(__bucket_type));
02110       return __p;
02111     }
02112 
02113   template<typename _NodeAlloc>
02114     void
02115     _Hashtable_alloc<_NodeAlloc>::_M_deallocate_buckets(__bucket_type* __bkts,
02116                                                         std::size_t __n)
02117     {
02118       typedef typename __bucket_alloc_traits::pointer _Ptr;
02119       auto __ptr = std::pointer_traits<_Ptr>::pointer_to(*__bkts);
02120       __bucket_alloc_type __alloc(_M_node_allocator());
02121       __bucket_alloc_traits::deallocate(__alloc, __ptr, __n);
02122     }
02123 
02124  //@} hashtable-detail
02125 _GLIBCXX_END_NAMESPACE_VERSION
02126 } // namespace __detail
02127 } // namespace std
02128 
02129 #endif // _HASHTABLE_POLICY_H